Schizofrenie je spojena s poškozením kognitivních funkcí, zejména pak s narušenou pozorností, pamětí a výkonovými funkcemi. I když Kraepelin či Bleuler se domnívali, že paměť u schizofrenie není výrazněji postižena, poslední studie svědčí o opaku. Není však zcela jasné, jaké funkce paměti jsou přesně u schizofrenie narušeny. Bylo zjištěno, že vybavování informací z dlouhodobé deklarativní paměti je u nemocných se schizofrenií narušeno více než vybavování informací z deklarativní paměti krátkodobé. Také se zdá, že ukládání do paměti „encoding“ je narušeno více než funkce vybavování „recall“ či znovu poznávání „recognition“. Jiní autoři ale na základě výsledků mnoha paměťových testů došli k závěru, že schizofrenie má deficitní všechny funkce paměti. Vzhledem k rozsahu poruchy se zdá být paměťový deficit spíše generalizovaný než diferencovaný a nelze jej vysvětlit pouhou narušenou soustředivostí.
Schizophrenia is connected with the defect of the cognitive functions. Besides the defect of power functions and attention it is especially memory that is defected. Though it is not clear enough, what functions of memory are exactly disrupted. It was found out, that recall of information from long-term declarative memory is in schizophrenia more defected then to recall of information from short-term declarative memory. It also seems, that saving information to the memory „ encoding“ is disrupted much more then the fuctions of bethinking of the information: „recall“ or „recognition“. Other authors, according to results from many memory tests, learned that schizophrenia makes all the functions of memory disrupted. Considering the dimension of the defect it appears that memory deficit is rather generalizated then differentiated and it can not be explained by only disturbed concentration.
BACKGROUND: Treating memory and cognitive deficits requires knowledge about anatomical sites and neural activities to be targeted with particular therapies. Emerging technologies for local brain stimulation offer attractive therapeutic options but need to be applied to target specific neural activities, at distinct times, and in specific brain regions that are critical for memory formation. METHODS: The areas that are critical for successful encoding of verbal memory as well as the underlying neural activities were determined directly in the human brain with intracranial electrophysiological recordings in epilepsy patients. We recorded a broad range of spectral activities across the cortex of 135 patients as they memorised word lists for subsequent free recall. FINDINGS: The greatest differences in the spectral power between encoding subsequently recalled and forgotten words were found in low theta frequency (3-5 Hz) activities of the left anterior prefrontal cortex. This subsequent memory effect was proportionally greater in the lower frequency bands and in the more anterior cortical regions. We found the peak of this memory signal in a distinct part of the prefrontal cortex at the junction between the Broca's area and the frontal pole. The memory effect in this confined area was significantly higher (Tukey-Kramer test, p<0.05) than in other anatomically distinct areas. INTERPRETATION: Our results suggest a focal hotspot of human verbal memory encoding located in the higher-order processing region of the prefrontal cortex, which presents a prospective target for modulating cognitive functions in the human patients. The memory effect provides an electrophysiological biomarker of low frequency neural activities, at distinct times of memory encoding, and in one hotspot location in the human brain. FUNDING: Open-access datasets were originally collected as part of a BRAIN Initiative project called Restoring Active Memory (RAM) funded by the Defence Advanced Research Project Agency (DARPA). CT, ML, MTK and this research were supported from the First Team grant of the Foundation for Polish Science co-financed by the European Union under the European Regional Development Fund.
- MeSH
- Humans MeSH
- Magnetic Resonance Imaging MeSH
- Brain Mapping MeSH
- Brain physiology MeSH
- Memory * physiology MeSH
- Prefrontal Cortex * physiology MeSH
- Mental Recall physiology MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- MeSH
- Hippocampus physiology MeSH
- Animals, Laboratory MeSH
- Cerebral Cortex physiology MeSH
- Memory MeSH
- Mammals MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Comparative Study MeSH
2nd ed. ix, 353 s. : il.
Pupil responses are known to indicate brain processes involved in perception, attention and decision-making. They can provide an accessible biomarker of human memory performance and cognitive states in general. Here we investigated changes in the pupil size during encoding and recall of word lists. Consistent patterns in the pupil response were found across and within distinct phases of the free recall task. The pupil was most constricted in the initial fixation phase and was gradually more dilated through the subsequent encoding, distractor and recall phases of the task, as the word items were maintained in memory. Within the final recall phase, retrieving memory for individual words was associated with pupil dilation in absence of visual stimulation. Words that were successfully recalled showed significant differences in pupil response during their encoding compared to those that were forgotten - the pupil was more constricted before and more dilated after the onset of word presentation. Our results suggest pupil size as a potential biomarker for probing and modulation of memory processing.
- MeSH
- Adult MeSH
- Cognition physiology MeSH
- Humans MeSH
- Young Adult MeSH
- Pupil physiology MeSH
- Mental Recall physiology MeSH
- Photic Stimulation MeSH
- Organ Size physiology MeSH
- Healthy Volunteers MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Young Adult MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Processing of memory is supported by coordinated activity in a network of sensory, association, and motor brain regions. It remains a major challenge to determine where memory is encoded for later retrieval. Here, we used direct intracranial brain recordings from epilepsy patients performing free recall tasks to determine the temporal pattern and anatomical distribution of verbal memory encoding across the entire human cortex. High γ frequency activity (65-115 Hz) showed consistent power responses during encoding of subsequently recalled and forgotten words on a subset of electrodes localized in 16 distinct cortical areas activated in the tasks. More of the high γ power during word encoding, and less power before and after the word presentation, was characteristic of successful recall and observed across multiple brain regions. Latencies of the induced power changes and this subsequent memory effect (SME) between the recalled and forgotten words followed an anatomical sequence from visual to prefrontal cortical areas. Finally, the magnitude of the memory effect was unexpectedly found to be the largest in selected brain regions both at the top and at the bottom of the processing stream. These included the language processing areas of the prefrontal cortex and the early visual areas at the junction of the occipital and temporal lobes. Our results provide evidence for distributed encoding of verbal memory organized along a hierarchical posterior-to-anterior processing stream.
- MeSH
- Time Factors MeSH
- Electrocorticography MeSH
- Gamma Rhythm physiology MeSH
- Humans MeSH
- Brain Mapping MeSH
- Cerebral Cortex physiology physiopathology MeSH
- Speech Perception physiology MeSH
- Drug Resistant Epilepsy physiopathology psychology MeSH
- Mental Recall physiology MeSH
- Vocabulary MeSH
- Visual Perception physiology MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Multicenter Study MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
The objective is to study the involvement of the posterior medial cortex (PMC) in encoding and retrieval by visual and auditory memory processing. Intracerebral recordings were studied in two epilepsy-surgery candidates with depth electrodes implanted in the retrosplenial cingulate, precuneus, cuneus, lingual gyrus and hippocampus. We recorded the event-related potentials (ERP) evoked by visual and auditory memory encoding-retrieval tasks. In the hippocampus, ERP were elicited in the encoding and retrieval phases in the two modalities. In the PMC, ERP were recorded in both the encoding and the retrieval visual tasks; in the auditory modality, they were recorded in the retrieval task, but not in the encoding task. In conclusion, the PMC is modality dependent in memory processing. ERP is elicited by memory retrieval, but it is not elicited by auditory encoding memory processing in the PMC. The PMC appears to be involved not only in higher-order top-down cognitive activities but also in more basic, rather than bottom-up activities.
- MeSH
- Acoustic Stimulation MeSH
- Adult MeSH
- Electroencephalography methods MeSH
- Epilepsy physiopathology MeSH
- Electrodes, Implanted MeSH
- Humans MeSH
- Brain physiology MeSH
- Memory physiology MeSH
- Signal Processing, Computer-Assisted MeSH
- Evoked Potentials, Auditory physiology MeSH
- Photic Stimulation MeSH
- Evoked Potentials, Visual physiology MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Male MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The way the human brain represents speech in memory is still unknown. An obvious characteristic of speech is its evolvement over time. During speech processing, neural oscillations are modulated by the temporal properties of the acoustic speech signal, but also acquired knowledge on the temporal structure of language influences speech perception-related brain activity. This suggests that speech could be represented in the temporal domain, a form of representation that the brain also uses to encode autobiographic memories. Empirical evidence for such a memory code is lacking. We investigated the nature of speech memory representations using direct cortical recordings in the left perisylvian cortex during delayed sentence reproduction in female and male patients undergoing awake tumor surgery. Our results reveal that the brain endogenously represents speech in the temporal domain. Temporal pattern similarity analyses revealed that the phase of frontotemporal low-frequency oscillations, primarily in the beta range, represents sentence identity in working memory. The positive relationship between beta power during working memory and task performance suggests that working memory representations benefit from increased phase separation.SIGNIFICANCE STATEMENT Memory is an endogenous source of information based on experience. While neural oscillations encode autobiographic memories in the temporal domain, little is known on their contribution to memory representations of human speech. Our electrocortical recordings in participants who maintain sentences in memory identify the phase of left frontotemporal beta oscillations as the most prominent information carrier of sentence identity. These observations provide evidence for a theoretical model on speech memory representations and explain why interfering with beta oscillations in the left inferior frontal cortex diminishes verbal working memory capacity. The lack of sentence identity coding at the syllabic rate suggests that sentences are represented in memory in a more abstract form compared with speech coding during speech perception and production.
- MeSH
- Adult MeSH
- Electrocorticography MeSH
- Memory, Short-Term physiology MeSH
- Middle Aged MeSH
- Humans MeSH
- Young Adult MeSH
- Brain physiology MeSH
- Speech Perception physiology MeSH
- Speech physiology MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Young Adult MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
BACKGROUND: Memory tests using controlled encoding and cued recall paradigm (CECR) have been shown to identify prodromal Alzheimer's disease (AD), but information about the effectiveness of CECR compared to other memory tests in predicting clinical progression is missing. OBJECTIVE: The aim was to examine the predictive ability of a memory test based on the CECR paradigm in comparison to other memory/non-memory tests for conversion to dementia in patients with amnestic mild cognitive impairment (aMCI). METHODS: 270 aMCI patients from the clinical-based Czech Brain Aging Study underwent a comprehensive neuropsychological assessment including the Enhanced Cued Recall test (ECR), a memory test with CECR, two verbal memory tests without controlled encoding: the Auditory Verbal Learning Test (AVLT) and Logical memory test (LM), a visuospatial memory test: the Rey-Osterrieth Complex Figure test, and cognitive testing based on the Uniform Data Set battery. The patients were followed prospectively. Conversion to dementia as a function of cognitive performance was examined using Cox proportional hazard models. RESULTS: 144 (53%) patients converted to dementia. Most converters (89%) developed dementia due to AD or mixed (AD and vascular) dementia. Comparing the four memory tests, the delayed recall scores on AVLT and LM best predicted conversion to dementia. Adjusted hazard ratios (HR) of immediate recall scores on ECR, AVLT, and LM were similar to the HR of categorical verbal fluency. CONCLUSION: Using the CECR memory paradigm in assessment of aMCI patients has no superiority over verbal and non-verbal memory tests without cued recall in predicting conversion to dementia.
Direct electrical stimulation of the brain has emerged as a powerful treatment for multiple neurological diseases, and as a potential technique to enhance human cognition. Despite its application in a range of brain disorders, it remains unclear how stimulation of discrete brain areas affects memory performance and the underlying electrophysiological activities. Here, we investigated the effect of direct electrical stimulation in four brain regions known to support declarative memory: hippocampus (HP), parahippocampal region (PH) neocortex, prefrontal cortex (PF), and lateral temporal cortex (TC). Intracranial EEG recordings with stimulation were collected from 22 patients during performance of verbal memory tasks. We found that high γ (62-118 Hz) activity induced by word presentation was modulated by electrical stimulation. This modulatory effect was greatest for trials with "poor" memory encoding. The high γ modulation correlated with the behavioral effect of stimulation in a given brain region: it was negative, i.e., the induced high γ activity was decreased, in the regions where stimulation decreased memory performance, and positive in the lateral TC where memory enhancement was observed. Our results suggest that the effect of electrical stimulation on high γ activity induced by word presentation may be a useful biomarker for mapping memory networks and guiding therapeutic brain stimulation.
- MeSH
- Adult MeSH
- Electric Stimulation * MeSH
- Electrocorticography * MeSH
- Gamma Rhythm physiology MeSH
- Middle Aged MeSH
- Humans MeSH
- Young Adult MeSH
- Cerebral Cortex physiology MeSH
- Memory physiology MeSH
- Drug Resistant Epilepsy physiopathology MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Young Adult MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Multicenter Study MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
